| 1. |
- Uhlemann, Elisabeth, et al.
(author)
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Deadline dependent coding-a framework for wireless real-time communication
- 2000
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In: Seventh International Conference on Real-Time Computing Systems and Applications. - Piscataway, NJ : IEEE. - 0769509304 ; , s. 135-142, s. 135-142
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Conference paper (peer-reviewed)abstract
- A framework for real-time communication over a wireless channel is proposed. The concept of deadline dependent coding (DDC), previously suggested by the authors, is further developed using soft decision decoding of block codes to maximize the probability of delivering information before a given deadline. The strategy of DDC is to combine different coding and decoding methods with automatic repeat request (ARQ) in order to fulfil the application requirements. These requirements are formulated as two Quality of Service (QoS) parameters: deadline (t_DL) and probability of correct delivery before the deadline (P_d), leading to a probabilistic view of real-time communication. An application can negotiate these QoS parameters with the DDC protocol, thus creating a flexible and dependable scheme.
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| 2. |
- Alexander, Paul D., et al.
(author)
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A linear receiver for coded multiuser CDMA
- 1997
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In: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 45:5, s. 605-610
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Journal article (peer-reviewed)
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| 3. |
- Alexander, Paul D., et al.
(author)
-
Filter structure for iterative signal processing
- 2002
-
Patent (pop. science, debate, etc.)abstract
- The present invention relates to improved multiple access communications. In one form, the invention relates to an improved signal processing method and apparatus for an iterative method of determining the reception of a signal in a multi user packet based wireless OFDM (Orthogonal Frequency Division Multiplexing) communication system. In other forms the present invention provides recursive filtering for joint iterative decoding in a variety of systems and functions such as linear multiple access channel decoders, iterative equalisation, iterative joint channel estimation and detection/decoding, iterative space-time processing, iterative multi user interference cancellation and iterative demodulation.; In one particular form the present invention provides an iterative decoding circuit for a wireless multiuser communications receiver comprising a first signal processing means for receiving at least one received signal, said first signal processing means comprising at least two linear iterative filters such that the first linear iterative filter provides an estimate of a selected received signal to an estimated signal output and a second linear iterative filter provides estimates of at least one other received signal, delayed by one iteration cycle, to an input of said first linear iterative filter, a second signal processing means for receiving the estimated signal output of the first linear iterative filter and providing a further received signal estimate to the input of the first signal processing means in a succeeding iteration cycle of the decoding circuit.
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| 4. |
- Alexander, Paul D., et al.
(author)
-
Filter structure for iterative signal processing
- 2002
-
Patent (pop. science, debate, etc.)abstract
- The invention is an iterative signal processing arrangement having one or more pairs of first and second signal processing components. These pairs are in iterative configuration with each of the first signal processing components having as its input one or more received signals dependent upon one or more transmitted signals. For each said signal processing component pair the output of said first signal processing component is an estimate of a characteristic of a selected transmitted signal based on the current and one or more previous input signals received by said first signal processing component. This estimate is input to said corresponding second signal processing component which provides a further estimate of said selected transmitted signal. The outputs of all said second components of respective pairs are input to their corresponding first components in a succeeding iteration cycle.
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| 5. |
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| 6. |
- Azmi, Marwan H., et al.
(author)
-
Design of Multi-Edge-Type Bilayer-Expurgated LDPC Codes for Decode-and-Forward in Relay Channels
- 2011
-
In: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 59:11, s. 2993-3006
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Journal article (peer-reviewed)abstract
- We consider the design of bilayer-expurgated low-density parity-check (BE-LDPC) codes as part of a decode-and-forward protocol for use over the full-duplex relay channel. A new ensemble of codes, termed multi-edge-type bilayer-expurgated LDPC (MET-BE-LDPC) codes, is introduced where the BE-LDPC code design problem is transformed into the problem of optimizing the multinomials of a multi-edge-type LDPC code. We propose two design strategies for optimizing MET-BE-LDPC codes; the bilayer approach is preferred when the difference in SNR between the source-to-relay and the source-to-destination channels is small, while the bilayer approach with intermediate rates is preferred when this difference is large. In both proposed design strategies multi-edge-type density evolution is used for code optimization. The resulting MET-BE-LDPC codes exhibit improved threshold and bit-error-rate performance as compared to previously reported bilayer LDPC codes.
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| 7. |
- Brännström, Fredrik, 1974, et al.
(author)
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A general structure for rate-compatible concatenated codes
- 2007
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In: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 11:5, s. 437-439
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Journal article (peer-reviewed)abstract
- In this letter, a general concatenated code structure is presented, encompassing both parallel and serially concatenated codes as special cases. The structure provides a unifying framework for the analysis of concatenated codes and offers new degrees of freedom for code design. Performance analysis based on error bounds in the error floor region and suggestions for suitable design criteria are provided, together with a design approach for the waterfall region. The proposed structure allows for constructing very high-rate codes with no penalty in the error floor region and good performance in the waterfall region.
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| 8. |
- Brännström, Fredrik, 1974, et al.
(author)
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Capacity considerations for trellis code multiple access systems
- 2001
-
In: IEEE Information Theory Workshop (ITW ’01), Cairns, Australia, Sept. 2001. ; , s. 153–-155, s. 153-155
-
Conference paper (peer-reviewed)abstract
- Trellis code multiple access (TCMA) is anarrow-band multiple access scheme. There is no bandwidthexpansion, so K users are using the same bandwidthas one single user. The load (the number of bits per channeluse) of the system is therefore much higher than the loadin, for example, conventional CDMA systems. It is shownhere that the maximum number of users in a TCMA systemis usually modest. This fact is based on constellationconstrainedcapacity, i.e., the maximum capacity of a systemwith a specific constellation of the transmitted symbols.The minimum required signal-to-noise ratio for reliabletransmission is also given for different code rates.
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| 9. |
- Brännström, Fredrik, 1974, et al.
(author)
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Classification of 8PSK mappings for BICM
- 2007
-
In: IEEE International Symposium on Information Theory. ; , s. 2136-2140, s. 2136-2140
-
Conference paper (peer-reviewed)abstract
- The performance of bit-interleaved coded modulation with iterative decoding is significantly influenced by the mapping of bits to the symbol constellation. A range of mappers have been suggested in the literature, however, no attempt has been made to systematically enumerate all unique mappers for a given signal constellation. In this paper, we classify 8PSK mappers based on bit-wise distance spectra for no prior information, and full prior information, respectively.
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| 10. |
- Brännström, Fredrik, 1974, et al.
(author)
-
Classification of Unique Mappings for 8PSK Based on Bit-Wise Distance Spectra
- 2009
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In: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 55:3, s. 1131-1145
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Journal article (peer-reviewed)abstract
- The performance of bit-interleaved coded modulation (BICM) with (or without) iterative decoding (ID) is significantly influenced by the mapping of bits to the symbol constellation. Our main objective in this paper is to develop a systematic design approach for BICM-ID schemes, ensuring the best possible performance with iterative decoding. Although useful mappings for BICM-ID have been found based on various search strategies, no attempt has been made to systematically enumerate and classify all unique mappers for a given constellation. As the basis for a systematic enumeration and classification, we define the average bit-wise distance spectrum for a mapping from bits to symbols. Different bit-wise distance spectra are derived assuming no prior information or full prior information, respectively. The bit-wise distance spectra determine corresponding bit-wise error probability and bit-wise mutual information. The latter allows us to use the classification of mappings with unique bit-wise distance spectra to also classify mappings with unique extremal points in the corresponding extrinsic information transfer (EXIT) curves. As an example of our approach, we classify 8PSK mappings into 86 classes of unique mappings according to bit-wise distance spectra. The classification can be used to significantly reduce the complexity of the search for suitable mappers for BICM-ID. For 8PSK and a given encoder, only 86 different mappings need to be, investigated. As examples of the systematic design approach, the best 8PSK mappings for minimizing the convergence threshold are found for concatenation with the rate 1/2 (5, 7)(8) and (133, 171)(8) convolutional codes, and the rate 1/2 UMTS turbo code with identical constituent convolutional codes (15/13)(8).
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